Observing with LOFAR FR606 : Semester 2014B
French LOFAR station Call for proposals
The LOFAR station FR606 is located in the Nançay Radio Observatory. It consists of two separate antenna arrays : the low band array (LBA, 96 dual polarisation antennas) and the high band array (HBA, 96 tiles of 16 dual-polarisation antennas). It is part of LOFAR (www.lofar.org), but it can also be used as a standalone instrument. Observations in “international mode” are handled by the International LOFAR Telescope (ILT) consortium. Observations in “stand-alone mode” are handled by a local committee.
Time is available to scientists from the worldwide community for observations with the French LOFAR station in "stand-alone mode" for the period December 2014 - May 2015. The telescope is open for teams from all countries (preferably including french members). The total available observing time is approximately 1-2 days/week. Observers are invited to visit Nançay to prepare the observations and plan the station configuration. Limited science support can be provided upon request, e.g. for the observations. Computing resources are available for data processing, but good knowledge of LOFAR data formats is recommended. All observations will be carried out in shared-risk mode. Observations and data processing can be controlled remotely. Proposals for Target Of Opportunity (TOO) observations will be considered at any time.
Deadline : 1 October 2014 (23:59:59 UTC)
Observing period : 1 December 2014 - 31 May 2015
The Nançay FR606 LOFAR station is located at Longitude 2°11.8’ E and Latitude 47°22.8’ N.
The French LOFAR station, in the standalone configuration offered here, covers the frequency ranges 10–90 MHz ("low band") and 110–240 MHz ("high band") in two orthogonal linear polarisations. The maximum bandwidth is 47.6 MHz (96 MHz in 8 bit mode), but the observation band does not need to be contiguous.
The following frequency settings are allowed :
|RCU mode||antenna set||accessible frequencies [MHz]||sampling frequency [MHz]|
The requested RCU mode(s) has to be indicated in the observation proposal.
The subbands bandwidth is given by sampling frequency/1024 (1st polyphase filter). The maximum total bandwidth is given by the product of subbands bandwidth and the number of subbands (244 for 16 bit mode, and twice that number for 8 bit mode), resulting in :
|sampling frequency [MHz]||bit mode||subbands bandwidth[kHz]||number of subbands||maximum total bandwidth [MHz]|
Sensitivity and beam width
The sensitivity and beam width of the French LOFAR station is approximately given by :
|beam FWHM [°]||23||11||8||6||5||3.3||2.6||2.2||1.9||1.7|
The SEFD (system equivalent flux density) is given for a single polarisation. The listed sensitivities are rms noise levels for 1 hour integration time x 12 MHz bandwidth (or 6 MHz x 2 polarisations). The beam FWHM (full width at half maximum) gives the approximate beam width.
The recommended elevation range is above 30° (thus 30°-90°).
1.) High cadence beamformed data : Up to 244 synthesized beams in the form of either complex wave data or Stokes IQUV data (the choice should be indicated in the proposal). Each beam is a subband of width 195 kHz at a cadence of 5.12 µs (156.250 kHz at a cadence of 6.4 µs for RCUMODE 6). In the normal operations mode, the maximum bandwidth for the high data-rate output is 48 MHz if all streams are beamformed in the same direction. Alternatively, in the other extreme case, 244 beams with different coordinates can be formed but will then only cover 195 kHz of bandwidth. There is thus a trade-off between number of beams and bandwidth per beam. The selected beam configuration should be indicated in the proposal. Further channelization can be requested to reduce the channel frequency width (typically, observations use up to 64 channels per subband). Automatic time integration is recommended to reduce the data volume.
2.) Low-cadence visibilities : Station visibility matrices can be dumped in files integrated over one second, but only for a single subband at a time.
3.) Full array waveform data using the Transient Buffer Boards ("TBB data") : Triggered capture of complex waveforms from all 96 individual LBA antenna elements, sampled at 200 MHz (5 ns time resolution) for a duration of up to 5 s.
- a cluster to record the high time resolution beam-formed data during the observation (named allegro1/2/3/4)
- a real-time pipeline for transient detection
- a socket for external triggering
- standard pulsar processing tools for offline processing
- two nodes for offline data processing (named nancep1/2)
- data storage (named databf)
- science support (observation planning and setup, observation)
Typical standalone programs
- Low resolution interferometric imaging of large sky areas (by correlating antenna signals)
- Tied-array observation of variable sources (with possible parametric dedispersion)
- Solar system observations (Sun, Jupiter, interplanetary scintillations...)
- Ionospheric monitoring (cutoff, absorption, scintillations, ...)
- Local emissions (meteors, cosmic rays, ...)
Proposal preparation and submission
The proposal should be submitted as one pdf file to firstname.lastname@example.org. The proposal must contain a front page with some basic information (see below), a proper and concise scientific justification including an explanation for how the requested observing time was estimated, no more than two A4 pages long, plus figures and tables if needed (for a total maximum of six pages, not including the front page).
The front page must contain :
- The title of the proposal.
- The observing period for the proposal.
- The name, affiliation, physical adress and email address of the principal investigator (PI).
- The names and affiliations of the co-investigators.
- The requested observing time.
- The requested processing resources.
- The requested storage resources.
- The requested science support.
- The requested RCU mode.
- An abstract.
There is currently no template file available.
All proposals will be evaluated by the FLOW/FR606 Programme Committee (coordinated by J.-M. Griessmeier). All proposals must be written in English.
- For more technical information, see LOFAR Technical Information (web site at ASTRON), in particular the pages about LOFAR stations : description and layout and Sensitivity of the LOFAR array. Also see the paper van Haarlem et al. (2013) : LOFAR : The LOw-Frequency ARray (A&A 556, A2 ; also available at astro-ph).
- Questions about the French LOFAR station : email@example.com.
- General questions about this proposal call : firstname.lastname@example.org.
Dernière modification le 10 mars 2015